1. Field of the Invention
The present invention relates to a data processing device preferably adopted to such as an electronic cash register for processing data sent from a host computer and data entered by operating keys thereof employed in a sales management system. An electronic cash register is provided in each of branch stores and the host computer is provided in a head office which is connected to each of the branch stores through one or more on-line circuits.
2. Description of the Prior Art
FIG. 1 shows a block diagram showing an outline of a sales management system comprising electronic cash registers D1 to Dn (represented as D hereinafter) according to the prior art, wherein the electronic cash registers D2 to Dn also have the same structures as that of the electronic cash register D1.
Each of the electronic cash registers D comprises three memory means 4a, 4b and 5 for example and a key input portion 6. Such an electronic cash register D with a structure as mentioned above is provided in each of the branch stores and is connected to a host computer 12 provided in a head or central processing office through one or more on-line circuits. In such a sales management system, all of the data such as sales data of the branch stores are sent from the electronic cash registers D to the host computer 12 through a communication line. The sent data is integrally processed for cash receipt/disbursement and stock management in the host computer 12.
When data of goods such as a unit price and a division code ("division" means a minimum sorting area consisting of goods in the same category having the same price assigned) of each of the goods are sent from the host computer 12 to the electronic cash register D provided in each of the branches, the data of the goods is first entered in the memory portion 4a of a buffer. This occurs so that the unit price of the goods, for example, is not updated during the process in the electronic cash register D, i.e., during the registering operation. Moreover, data of goods can be written in the memory 4b by operating the key input portion 6 so that the unit price of the goods, for example, can be decided in each of the branches individually.
The data of goods to be entered in the memories 4a and 4b have priorities respectively defined and, for example, in case two different unit prices for the same goods are respectively stored in the memories 4a and 4b, the data stored in the memory 4a is transferred to the memory 4b in order to store the data with a higher priority in the memory 4b. Therefore each of the two kinds of data are combined. When the transfer of the data from the memory 4a to the memory 4b is completed, the memory content of the memory 4a is deleted.
Subsequently, the combined data of goods stored in the memory 4b are transferred to the memory 5. The data of goods such as a unit price and a division code of the goods are then entered in the electronic cash register D so that the processes according to the entered data are performed.
In the electronic cash register D as described above in the prior art, when a data is transferred from the memory 4b to the memory 5 for example, there may occur an error due to, for example, a lack of the capacity of the memory 5. In such a case, the data stored in the memory 4a has already been deleted and it can not be judged whether also the data stored in the memory 4b is the data written in the memory 4b by operating the key input portion 6 or the data transmitted from the host computer 12. Therefore, if such an error occurs, a part of the data is lost, resulting in a large hindrance caused in the sales management system.